The present invention relates to an integrally molded, fiber-reinforced resin unit, a flow-rectifying member constituted by an assembly of such units and a method for producing such a flow-rectifying member, particularly to an I- or C-shaped unit comprising a fiber-reinforced core and a resin skin layer integrally molded therewith, a flow-rectifying member constituted by annularly combining such units, and its production method.
Because gas turbine engines not only produce large output but also are extremely efficient, they are widely used for aircraft, electric generators, etc. For instance, gas turbine engines for aircraft are provided with stator vanes acting to guide the introduced air to rotor vanes and working as outlet guide vanes for rectifying a bypass flow. The stator vanes are generally made of metal materials such as titanium alloys, aluminum alloys, stainless steel, etc. The metal stator vanes are produced by forming vanes by casting, forging, pressing, etc., and bonding each vane to a casing called a platform by welding or brazing, etc.
However, the above conventional production methods need machining, finishing, coating, etc. after the formation of vanes, resulting in a large number of working steps and the difficulty of working of small complicated parts. In addition, because they use metal members, the resultant flow-rectifying members are heavy and expensive.
Thus, attention has recently been paid to methods for producing stator vanes by resins or resin composite materials, and several proposals have been made so far. For instance, JP 5-278063A discloses a method for producing vane parts comprising the steps of laminating prepregs to form vane bodies having a smaller size than a desired vane shape; introducing each vane body into a mold to obtain the desired vane shape; and charging a thermoplastic resin into a gap between the vane body and the mold under pressure to carry out compression molding. With stator vanes made of resins, a production period can be shortened with simplified operation and improved shape precision, thereby achieving substantial reduction of cost and weight, etc. However, because resin vane parts are mounted onto platforms by an adhesive or bolts, etc. to produce stator vanes, the stator vanes have many constituent elements, resulting in increase in production steps.
Also, because a thermoplastic resin (polyetheretherketone: PEEK) for a skin layer has as high a melting point as 345xc2x0 C., it has low flowability in a molten state, resulting in the limitations in a vane design that it is difficult to make the skin layer of the stator vane thinner, and that shrinkage deformation is likely to occur at the time of integral molding. Further, the resin vane parts have insufficient abrasion resistance to sand, etc.
As described in JP 11-350904 A, the conventional flow-rectifying member is produced by bonding units one by one by an adhesive, etc. to assemble a structure, and then fixing the structure by winding tapes, etc. around it. However, such a method cannot provide the flow-rectifying member with a uniform shape without difficulty because of the tolerance of units, resulting in difficulty in fixing at desired positions. In addition, an additional operation of fixing units by winding tapes is needed, and even when one of the units is damaged, the entire flow-rectifying member should be exchanged.
Accordingly, an object of the present invention is to provide a flow-rectifying member unit having high strength and excellent abrasion resistance with a high degree of freedom in design.
Another object of the present invention is to provide a flow-rectifying member having high strength and excellent abrasion resistance, which is constituted by assembling such units with exchangeability of each unit.
A further object of the present invention is to provide a method for producing such a flow-rectifying member.
As a result of intense research in view of the above objects, the inventors have found that (a) by forming an I- or C-shaped unit for constituting a flow-rectifying member by integrally molding a rubber or a thermosetting resin having rubber elasticity around its core, and by combining these flow-rectifying member units annularly, it is possible to easily produce a flow-rectifying member having high strength, excellent abrasion resistance and a uniform shape with exchangeability of each unit, and that (b) by connecting the outer and inner platform pieces of the above units respectively to those of the adjacent units to form a temporary assembly, and by fixing it to support members and fixing members, it is possible to easily produce a flow-rectifying member. The present invention has been completed based on these findings.
The flow-rectifying member unit of the present invention used for assembling a flow-rectifying member comprising a plurality of vanes, an outer platform and an inner platform has an integral structure comprising a vane, an outer platform piece and an inner platform piece, the unit being constituted by (a) a core comprising a web constituting the vane, and flanges integrally connected to both ends of the web for constituting the outer platform piece and the inner platform piece, and (b) a skin layer covering a surface of the core; and the skin layer being made of a rubber or a thermosetting resin having rubber elasticity.
The flow-rectifying member of the present invention comprises a plurality of vanes, an outer platform and an inner platform for having a flow-rectifying function to a fluid flowing thereinto, which is integrally constituted by annularly connecting a plurality of flow-rectifying member units each having an integral structure comprising a vane, an outer platform piece and an inner platform piece, with the adjacent outer platform pieces connected to each other, and with the adjacent inner platform pieces connected to each other; each flow-rectifying member unit comprising (a) a core comprising a web constituting the vane, and flanges integrally connected to both ends of the web for constituting the outer platform piece and the inner platform piece, and (b) a skin layer covering a surface of the core; and the skin layer being made of a rubber or a thermosetting resin having rubber elasticity.
The method of the present invention for producing a flow-rectifying member comprises the steps of (1) forming a core comprising a vane, an outer platform piece and an inner platform piece by integrally connecting flanges to both ends of a web constituting the vane, and integrally molding a skin layer made of a rubber or a thermosetting resin having rubber elasticity to a surface of the core, thereby forming a flow-rectifying member unit; (2) connecting the outer platform pieces of the adjacent units to each other, and connecting inner platform pieces of the adjacent units to each other, thereby forming an annular temporary assembly; (3) mounting the outer and inner platforms of the temporary assembly onto outer and inner circular support members, respectively; and (4) fixing outer and inner fixing members respectively to the outer and inner circular support members, thereby fixing the temporary assembly to the outer and inner fixing members.
The rubber or the thermosetting resin having rubber elasticity is preferably a thermosetting urethane rubber, and the core is constituted by a laminate of fiber-reinforced prepregs or a light metal. The flanges are preferably formed by bending both end portions of the laminate of the fiber-reinforced prepregs. The fiber-reinforced prepregs are preferably carbon-fiber-reinforced polyetheretherketone or a carbon-fiber-reinforced epoxy resin, and the light metals are preferably aluminum alloys or magnesium alloys.
Each of the outer platform piece and the inner platform piece has connecting step portions at both ends, and the step portions of the adjacent units have shapes complementary to each other.
The unit according to a preferred embodiment of the present invention comprises flanges obtained by dividing both end portions of the laminate of the fiber-reinforced prepregs to two and bending them in a T shape, whereby a core has a substantially I shape. The unit according to another preferred embodiment of the present invention comprises flanges obtained by bending both end portions of the laminate of the fiber-reinforced prepregs in the same direction, whereby a core has a substantially C shape.
The adjacent outer platform pieces are overlapping each other via their connecting step portions, and the adjacent inner platform pieces are overlapping each other via their connecting step portions.
The outer and inner platforms are preferably fixed by outer and inner circular support members and outer and inner fixing members, respectively. Each of the outer, circular support member and the inner circular support member preferably comprises a receiving portion having a width equal to or slightly smaller than the thickness of one end portion of each of the outer platform and the inner platform, whereby one end portion of each of the outer platform and the inner platform is press-fitted into the receiving portion of each of the outer, circular support member and the inner circular support member.
The outer fixing member and/or the inner fixing member is annular and has stoppers projecting from one surface thereof, and the stoppers are caused to engage notches of the outer platform and/or the inner platform of the temporary assembly to fix the temporary assembly at a predetermined position.
In a preferred embodiment, the outer and inner platform pieces respectively have connecting step portions at both ends, the step portions being overlapping with the complementarily shaped step portions of the adjacent units, whereby the outer platform pieces are connected to each other, and the inner platform pieces are connected to each other, both by an elastic function of the rubber or the thermosetting resin having rubber elasticity.
The outer, circular support member preferably has, on an inner surface, a receiving portion, to which an outer platform of the temporary assembly is mounted.
The flow-rectifying member of the present invention is preferably a stator vane assembly of a gas turbine.